Paving Stones, Method for Laying Pavement with Same and Method for Producing Same

ABSTRACT

The invention relates to a set of paving stones having different thicknesses with respect to each other. At least one oblong recess is provided in the bottom side of each of the paving stones of the set, said oblong recess extending from one lateral side of the stone up to another lateral side, having a continuous cross-section and being provided for accommodating a complementary, regularly shaped carrier onto which the paving stones are to be laid. For each paving stone the/each recess extends into the bottom side of the paving stone up to a predetermined first distance (h) from a tangent plane to the top side, said predetermined first distance (h) being substantially the same for all paving stones of the set. The invention further relates to a method for laying a pavement with these paving stones and a method for producing these paving stones.

TECHNICAL FIELD

The present invention relates to a set of paving stones, a method forlaying a pavement with these paving stones and a method for producingthese paving stones.

BACKGROUND ART

Natural hewn stones, such as for example cobblestones and the like, haveirregular, rough surfaces as a result of the fact that they were hewnout of rocks in quarries. The dimensions of the stones are also notuniform. As a result of these irregular features, the laying ofpavements with these stones involves more skill than just placing thestones on the sand bed or foundation bed as is the case with pavingstones of uniform dimensions and more even surfaces such as for examplecut tiles, concrete tiles or paving stones, brick stones or other stoneswith fixed dimensions. Upon laying a pavement with natural hewn stones,the worker has to take the variations in thickness and the unevenness ofthe surfaces into account (see FIG. 1), since it is desired that the topsurface of the pavement is as flat as possible. As a result, laying apavement with natural hewn stones or irregularly shaped paving stones isa time consuming operation which requires a high degree ofcraftsmanship.

More in general, similar problems could arise with “regular” pavingstones which are produced with too much tolerance, i.e. too muchdeviations in the dimensions of one stone with respect to another.

A solution could be to unite the paving stones to a larger prefabricatedplate of a uniform size, such as for example described in DE-A-19801378.This however has the disadvantage that larger plates of paving stoneshave to be treated upon laying the pavement, which may be too large andtoo heavy to manipulate by hand, so that machinery is necessary.Furthermore, such methods are bound to a limited number of stone types,colours and sizes and the size of the plate is fixed, all of whichlimits the flexibility of application and the possibility to choose andvary stones in the pavement.

DISCLOSURE OF THE INVENTION

It is an aim of the present invention to provide paving stones withwhich a pavement can be constructed more quickly without necessitatingthe use of machinery or special tools like a mallet or such.

This aim is achieved according to the invention with the set of pavingstones showing the technical features of claim 1.

It is also an aim of the present invention to provide a method forlaying a pavement in which the paving stones are still placed one by onebut at a higher pace.

This aim is achieved according to the invention with the methodcomprising the steps of claim 7.

It is furthermore an aim of the present invention to provide acost-efficient method for producing the paving stones of the invention.

This aim achieved according to the invention with the method comprisingthe steps of claim 15.

As used herein, a “pavement” is intended to mean the durable surface ofroads, walkways, driveways, terraces etc.

Each stone of a set of paving stones according to the invention has atop side, a bottom side and a plurality of lateral sides which extendfrom the top side to the bottom side. The top, bottom and lateral sidesmay each have an even or an uneven surface. The thickness of the stones,measured between parallel tangent planes to the top side and the bottomside, differs to a given extent from one stone to the other, i.e. thestones do not have a uniform thickness. According to the invention, atleast one oblong recess is provided in the bottom side of each of thepaving stones. This recess extends from one lateral side of the stone toanother and has a continuous cross-section, so that it is adapted foraccommodating a complementary, regularly shaped carrier onto which thepaving stones are to be laid on top of the foundation bed. For eachpaving stone, each oblong recess extends into the bottom side of thestone up to a first distance from the tangent plane to the top side.This first distance is a predetermined distance which is the same forall paving stones of the set.

In laying a pavement with the paving stones of the invention, carriers,shaped complementary to the oblong recesses in the bottom side of thepaving stones, are first placed on top of an evened-out foundation bed,after which the paving stones are placed on top of the carriers. As aresult of the predetermined distance between the top of each recess andthe tangent plane to the top side of the stone, which distance isuniform for all of the stones, the tangent planes to the top sides ofall the stones end up in substantially the same plane. Usually, thoughnot essentially, the pavement will be finished by compacting it by meansof a compacting device and by filling the joints by means of a suitablefiller material.

As a result of the use of the carrier and the complementary recesses inthe bottom side of the stones, differences in thickness of the stones dono longer have to be taken into account upon laying each stone bypressing it more or less into the foundation bed, as it is done up tonow. As a result, less skilled workers can lay a pavement with thepaving stones of the invention. For example, in the case of naturalstone pavements, the laying is no longer the privilege of a limitednumber of craftsmen. This is advantageous, since the craftsmanship oflaying for example a cobblestone pavement is no longer passed on fromfather to son as much as in earlier days, so the number of skilledcraftsmen is ever reducing.

With the stones of the invention, whether they are natural stones orman-made stones, pavements can now be laid by less skilled workerswithout affecting the quality of the end result since differences inthickness are still overcome without requiring the workers to locallyadapt the height of the foundation bed to the thickness of the stone. Infact, the quality of the end result may even be enhanced, since thecarriers which engage in the recesses of the stones function asadditional stabilisers for the stones.

Furthermore, with the paving stones of the invention, a pavement can belaid at a higher pace with respect to the prior art. Up to now, theskilled worker had to adjust the position of each stone individuallydirectly after it was laid on the foundation bed by tapping it by malletinto the foundation bed to a given extent to overcome the thickness andby repositioning the stone until the joint with the adjacent stones wasacceptable, etc. With the paving stones of the invention, the variationsin thickness are already overcome once the stone is laid and the jointcan also immediately be fixed by the carrier, so that the pavementlaying pace can be highly enhanced, also because the worker now has bothhands available for laying stones. This limits the duration of roadblocks and other inconveniences in cities and municipalities, especiallysince a pavement laid with stones according to the invention isimmediately stabilised by the carriers, so that people can be allowed towalk over the newly laid pavement before it is finally finished bycompacting and filling the joints.

The fact that the recess in the bottom side of the stone is an oblongrecess extending from one lateral side up to another lateral side hasthe advantage that oblong carriers can be used which support multiplestones and thus further stabilise the pavement, and that there is stilla degree of freedom in the axial direction of the recess so that stonesof different lengths (in axial direction of the recess) can be laidrandomly and that the width of the joints on either end of the recesscan be adapted at will, since the stones can be moved in axial directionof the recesses along the carriers until the optimal position isreached. So the use of the carriers does also not put a bar on thecreativity.

In a preferred embodiment of the invention, the paving stones aregenerally parallelepiped-shaped, meaning that they have two pairs ofsubstantially parallel lateral sides which are substantiallyperpendicular to the top and bottom sides. In this embodiment,preferably two recesses are provided in the bottom side of each stonealong one of said pairs of lateral sides of the stone. These tworecesses are preferably spaced a predetermined second distance from eachother, which is again substantially the same for all paving stones ofthe set. With this embodiment, oblong carriers are used which definerows or columns of paving stones of the pavement, which can simplify thelaying of the pavement and thus can further enhance the pace at whichthe pavement can be laid. The worker can now simply place the carriersfor a new row at the second distance from the carriers supporting theprevious row of paving stones and then place the paving stones on top ofthe carriers.

Preferably the two recesses are open towards the lateral sides of thestones, so that each carrier can be used for supporting two adjacentpaving stones. Preferably a central portion of the bottom side of thestone which is delimited by the two recesses is on average about in themiddle of the stone. This means that the lateral sides of the pavingstones protrude substantially always the same distance over thecarriers. This can substantially fix the width of the joints betweenadjacent rows of paving stones, thus avoiding irregularities and thusinstabilities in the pavement.

Preferably, each of the recesses in the stone comprises a top sidesubstantially parallel to the tangent plane to the top side of the stoneand a lateral side substantially perpendicular to said top side. Morepreferably, each of the recesses is adapted for accommodating aparallelepiped-shaped carrier. This enables the use of carriers with arectangular cross-section such as for example wooden beams, which arewidely available and thus cheap. However, this does not preclude the useof other carriers in other materials and with other shapes, such as forexample carriers made of metal, stone, a plastic material or for examplea recycled plastic and having triangular, trapezoidal, semi-circular,circular, stepped or other cross-sections.

The paving stones of the invention can for example be natural hewnstones, such as for example cobblestones, of which most or all sideshave uneven surfaces, or any other natural or man-made paving stonesknown to the person skilled in the art. The invention can for examplealso be applied for mixing different types of stones with each other,i.e. for example for laying pavements which partly comprise naturalstones and partly comprise man-made stones.

The method for laying a pavement according to the invention makes use ofone of the above described embodiments of paving stones. The method forlaying a pavement comprises the following steps. First, a foundation bedis evened out. Next, regularly shaped carriers are placed on thefoundation bed, each of said carriers being complementary to therecesses in the bottom sides of the paving stones. Then, the pavingstones are placed on the carriers, such that the carriers engage in therecesses and the tangent planes of the top sides of the paving stonesare located substantially in the same plane.

The advantages of the method for laying a pavement of the invention havealready been described above and will therefore not be repeated here.

The carriers are preferably placed at about a predetermined thirddistance from each other which corresponds to the distance between twosuccessive recesses in the bottom side of one stone or in the bottomsides of two successive rows of stones, depending on the paving stoneswhich are used.

Preferably most of the carriers have lengths which span multiple pavingstones, so that they support two or more paving stones. This can furtherenhance the stability of the pavement.

The carriers can for example be laid in rows or columns, or in bows,circles or in a fan-shaped pattern, or according to any other patternknown to the person skilled in the art, depending on the desired patternfor the pavement or the general shape of the paving stones.

The carriers are preferably parallelepiped-shaped with a rectangularcross-section, but any other geometrical shapes are also possible, suchas for example triangular, trapezoidal, semi-circular, circular, steppedor other cross-sections. In an embodiment according to the invention,the carriers have wider sides and narrower sides and are placed on thefoundation bed by means of one of the wider sides. The carriers may alsobe placed on one of the narrower sides, which may for example be usefulon a side of the pavement against a wall.

In a preferred embodiment of the method for laying a pavement accordingto the invention, the carriers are placed in fixed relationship withrespect to each other by means of fixing means, according to apredetermined pattern in which the paving stones are to be laid. Thefixing means can for example be formed by screws or nails which anchorthe carriers to a foundation or to each other. This embodiment canfurther enhance the stability of the pavement.

The method for laying a pavement according to the invention may furthercomprise at least one of the following steps: compacting the pavement bymeans of a compacting device and/or filling joints in between the pavingstones of the pavement by means of a filling material. These steps areknown in the art and need no further explanation.

The method for producing the stones according to the inventionpreferably comprises the step of creating the recesses by cutting ormilling material from the bottom side of each stone. This is a quick andthus advantageous way to create the recesses. This way of creating therecesses can conveniently be automated, so that the paving stones of theinvention can be produced on an assembly line. For example, the stonescan be placed upside down on a conveyor belt and pass through acutting/milling machine for creating the recesses. This is convenientsince the conveyor belt then corresponds to the tangent plane to the topside of the stones.

In a preferred embodiment of the method of the invention, two recessesare created in the bottom side along one pair of lateral sides of thestone and two further recesses are created in the top side of eachstone, along the same pair of lateral sides as where the recesses at thebottom side are located. Then, each stone is divided up into two partsgenerally along a plane parallel or perpendicular to said tangent planeto the top side of the stone. In this way, two paving stones can beconstructed from one block of stone.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be further elucidated by means of the followingdescription and the appended figures.

FIG. 1 shows a plurality of prior art paving stones.

FIG. 2 shows how paving stones are adapted according to an embodiment ofthe invention.

FIGS. 3 and 4 show how a pavement is laid according to an embodiment ofthe invention.

MODES FOR CARRYING OUT THE INVENTION

The present invention will be described with respect to particularembodiments and with reference to certain drawings but the invention isnot limited thereto but only by the claims. The drawings described areonly schematic and are non-limiting. In the drawings, the size of someof the elements may be exaggerated and not drawn on scale forillustrative purposes. The dimensions and the relative dimensions do notnecessarily correspond to actual reductions to practice of theinvention.

Furthermore, the terms first, second, third and the like in thedescription and in the claims, are used for distinguishing betweensimilar elements and not necessarily for describing a sequential orchronological order. The terms are interchangeable under appropriatecircumstances and the embodiments of the invention can operate in othersequences than described or illustrated herein.

Moreover, the terms top, bottom, over, under and the like in thedescription and the claims are used for descriptive purposes and notnecessarily for describing relative positions. The terms so used areinterchangeable under appropriate circumstances and the embodiments ofthe invention described herein can operate in other orientations thandescribed or illustrated herein.

The term “comprising”, used in the claims, should not be interpreted asbeing restricted to the means listed thereafter; it does not excludeother elements or steps. It needs to be interpreted as specifying thepresence of the stated features, integers, steps or components asreferred to, but does not preclude the presence or addition of one ormore other features, integers, steps or components, or groups thereof.Thus, the scope of the expression “a device comprising means A and B”should not be limited to devices consisting only of components A and B.It means that with respect to the present invention, the only relevantcomponents of the device are A and B.

The problem underlying the invention is clarified by means of FIG. 1. Anumber of natural paving stones 1, 2, 3, 4 of generally parallelepipedshape with hewn surfaces are shown, with their top sides substantiallyin the same plane. As shown, the thickness H of these stones, which ismeasured between a tangent plane to the top side and a parallel tangentplane to the bottom side, varies from one stone to another to a largeextent. The dimensions of the stones 1, 2, 3, 4 are also not uniform. Asa result of these irregular features, the laying of pavements with thesestones involves more skill than just placing the stones on the sand bedor foundation bed as is the case with paving stones of uniformdimensions and more even surfaces such as for example cut tiles,concrete tiles or paving stones, brick stones or other stones with fixeddimensions. Upon laying a pavement with these natural hewn stones, theworker has to take the variations in thickness H and the unevenness ofthe surfaces into account, since it is desired that the top surface ofthe pavement is as flat as possible. As a result, laying a pavement withthese natural hewn stones 1, 2, 3, 4 is a time consuming operation whichrequires a high degree of craftsmanship.

FIG. 2 shows how this problem is tackled according to the invention. Onthe left, an irregularly shaped paving stone 5 is shown before treatmentand on the right, an irregularly shaped paving stone 6 is shown aftertreatment according to the invention. The thickness H of the stone 6 hasbeen laterally reduced to a thickness h by cutting recesses 7, 8 ofaverage height h1 into the bottom side 9 of the stone 6. The top sides11, 12 of the recesses 7, 8 are parallel to the tangent plane to the topside 10 of the stone 6, so that the reduced thickness h is substantiallyconstant over the full length of the stone.

The recesses 7, 8 furthermore have an average width b1 and define acentral portion 15 on the bottom side 9 of the stone 6 which isdelimited by their lateral sides 13, 14. The width b1 of the recesses 7,8 is chosen such that variations in the width B of the stone are fullytaken up by the recesses 7, 8, so that the reduced width b also becomesa substantially constant value over the full length of the stone. Sincethe recesses 7, 8 of substantially the same width b1 extend on eitherside of the central portion 15 of the bottom side of the stone, thecentral portion 15 is centred.

It can thus be stated that H=h+h1 and B=b1+b+b1. The result of therecesses 7, 8 is that from stones 5 with large variations in thickness Hand width B, stones 6 are produced with a constant reduced thickness hand a constant and centred reduced width b.

With treated paving stones 6, a pavement is now laid as shown by meansof FIGS. 3 and 4. A foundation bed 16 is evened out, which may forexample comprise sand, a mixture of sand and cement, concrete or anyother foundation bed known to the person skilled in the art. Then,carriers 17 are placed on the foundation bed 16 at regular distancesfrom each other, such that the central portions 15 of the bottom sides 9of the stones 6 can be accommodated between them. Afterwards, the stones6 are placed on the carriers 17, such that the carriers 17 engage in therecesses 7, 8 and the top sides 10 of the stones 6 become located insubstantially the same plane. In this way, the pavement can be laidquickly by relatively less skilled workers, since irregularities in thedimensions of the stones are immediately overcome and there is no longera need to locally adapt the foundation bed.

The carriers 17 have a rectangular cross-section with dimensions E×h2,preferably E being greater than 2×b1 and h2 being greater than h1, sothat the variations in the dimensions of the stones 6 are fully taken upby the carriers 17, leading to joints 18 of average width e between thestones 6.

The stones 6 are supported both vertically and horizontally, since thelateral sides 13, 14 of the recesses 7, 8 lie against the carriers 17.As a result, rotations or displacements of the stones 6 are prevented.

The carriers 17 can be laid in rows or columns, or in bows, circles orin a fan-shaped pattern, or according to any other pattern known to theperson skilled in the art, depending on the desired pattern for thepavement or the general shape of the paving stones.

Optionally, though not necessarily, the resulting pavement can befinished by compacting it by means of a compacting device and by fillingthe joints by means of a suitable filler material. It can for example beadvantageous to leave the joints between the stones open for evacuationof rain water, or to have a floating pavement of which the stonesthemselves do not rest on the foundation bed.

Optionally, though not necessarily, the carriers 17 may be anchored tothe foundation bed 16 or otherwise brought in fixed relationship witheach other before laying the stones 6 on top of them.

The paving stones 6 shown in FIGS. 2-4 are generallyparallelepiped-shaped. However, other shapes are also possible. Therecesses 7, 8 have perpendicular sides 11, 12, 13, 14 so that they areadapted for accommodating parallelepiped-shaped carriers 17, but theymay also be shaped for accommodating carriers with triangular,trapezoidal, semi-circular, circular, stepped or other cross-sections.The paving stones 6 are natural stones with hewn surfaces, but theinvention may also be applied to paving stones with even surfaces and/ormore regular dimensions, such as for example concrete tiles etc. ofwhich the variation of the dimensions is unsuitably large.

The paving stones 6 shown in FIGS. 2-4 have a recess 7, 8 on either sideof the bottom side 9. Alternatively, a single oblong recess preferablysubstantially in the middle of the bottom side may also be used, ormultiple recesses, not necessarily on the lateral sides of the stones 6.Recesses may furthermore be applied in directions which cross eachother.

The carriers 17 may be constructed in wood, stone, metal, a plasticmaterial or any other material known to the person skilled in the art.Preferably, carriers in recycled plastics are used for ecologicalreasons.

1. A set of paving stones, each having a top side, a bottom side and aplurality of lateral sides extending from the top side to the bottomside, the paving stones having different thicknesses which vary to alarge extent with respect to each other, the thickness of each stonebeing measured between parallel tangent planes to the top and bottomsides of the stone, wherein at least one oblong recess is provided inthe bottom side of each of the paving stones of the set, said oblongrecess extending from one lateral side of the stone up to anotherlateral side, having a continuous cross-section and being provided foraccommodating a complementary, regularly shaped carrier onto which thepaving stones are to be laid, and wherein for each paving stone the/eachrecess extends into the bottom side of the paving stone up to apredetermined first distance (h) from a tangent plane to the top side,said predetermined first distance (h) being substantially the same forall paving stones of the set and being provided for overcoming thedifferences in thickness.
 2. A set of paving stones according to claim1, wherein each stone is generally parallelepiped-shaped with two pairsof substantially parallel lateral sides extending from the top side tothe bottom side, two of said recesses being provided in the bottom sideof each stone along one of said pairs of lateral sides of the stone,said two recesses being spaced a predetermined second distance (b) fromeach other, said predetermined second distance (b) being substantiallythe same for all paving stones of the set.
 3. A set of paving stonesaccording to claim 2, wherein said two recesses are open towards thelateral sides and wherein a central portion of the bottom side of thestone delimited by the two recesses is on average about in the middle ofthe stone.
 4. A set of paving stones according to claim 1, wherein eachof said recesses comprises a top side substantially parallel to saidtangent plane to the top side of the stone and a lateral sidesubstantially perpendicular to said top side.
 5. A set of paving stonesaccording claim 1, wherein each of said recesses is adapted foraccommodating a parallelepiped-shaped carrier.
 6. A set of paving stonesaccording to any claim 1, wherein the stones are natural hewn stones ofwhich at least one of the sides has an uneven surface.
 7. Method forlaying a pavement by means of paving stones according to claim 1, themethod comprising the step of: a) evening out a foundation bed, whereinthe method further comprises the steps of: b) placing oblong carriers onthe foundation bed, each of said oblong carriers being regularly shapedand being complementary to the recesses which are provided in the bottomsides of the paving stones, c) placing the paving stones on thecarriers, such that the carriers engage in the recesses and the tangentplanes of the top sides of the paving stones are located substantiallyin the same plane.
 8. Method for laying a pavement according to claim 7,wherein in step b) the carriers are placed at about a predeterminedthird distance (b) from each other, said third distance (b)corresponding to the distance between two successive recesses in thebottom sides of the stones.
 9. Method for laying a pavement according toclaim 7, wherein most of the carriers have lengths which span multiplepaving stones.
 10. Method for laying a pavement according to claim 7,wherein the carriers are laid in rows, bows, circles or in a fan-shapedpattern.
 11. Method for laying a pavement according to claim 7, whereinthe carriers are parallelepiped-shaped.
 12. Method for laying a pavementaccording to claim 11, wherein the carriers have wider sides andnarrower sides, the carriers being placed on the foundation bed by meansof one of the wider sides.
 13. Method for laying a pavement according toclaim 7, wherein the carriers are placed in fixed relationship with eachother by means of fixing means according to a predetermined pattern inwhich the paving stones are to be laid.
 14. Method for laying a pavementaccording to claim 7, wherein the method further comprises at least oneof the following steps: d) compacting the pavement by means of acompacting device, e) filling joints in between the paving stones of thepavement by means of a filling material.
 15. Method for producing pavingstones according to claim 1, wherein the recesses are created by cuttingor milling material from the bottom side of each stone.
 16. Method forproducing irregularly shaped paving stones according to claim 15,wherein the paving stones are generally parallelepiped-shaped with twopairs of substantially parallel lateral sides extending from the topside to the bottom side, and two of said recesses are created in thebottom side of each stone along one of said pairs of lateral sides, andwherein the method further comprises the steps of creating two furtherrecesses in the top surface of each stone along said one pair of lateralsides, and dividing the stone up into two parts substantially along aplane parallel or perpendicular to said tangent plane to the top side ofthe stone.